Last week's Algerian gas field siege and hostage taking, unforeseen by its victims and dreadful in its consequences, came like a bolt from the blue. How many Britons or Americans, or Norwegians for that matter, were even aware that BP and other energy companies were operating in the remote Sahara? Who until now had heard of Mokhtar Belmokhtar, otherwise known as Mr Marlboro, the cigarette-smuggling jihadist who supposedly masterminded the Ansema assault? Not David Cameron perhaps, though, with the benefit of a Cobra briefing or two, he was quick to blame the Islamist leader for the violence in his Commons statement on Friday. Who would have thought that what started as a spot of local trouble in little-known Mali could end up sending the world's most powerful leaders scurrying for their hotlines, their military top brass on red alert, their specialist hostage rescue teams chomping at the bit for the call that never came?

Yet one might ask, with equal earnestness: why the surprise? For is this not the way of the world in our interconnected, endlessly informed, wholly interdependent 21st century? For the purposes of international security, as defined by the west, and for the purposes of global jihad, as promoted by al-Qaida, its affiliates and copycat groups, southern Algeria, a Muslim country with a long history of hardline Islamist agitation, is as good a theatre as any for the next act of their ongoing, many faceted confrontation, and perhaps better in some significant respects. The first lesson to be drawn from the sudden, unexpected French military intervention in Mali is that, whenever or wherever such events occur these days, the impact and the potentially heartrending consequences will be felt, randomly and unpredictably, around the globe, reaching out from the immediate neighbourhood to the distant homes of worried relatives in Bergen, Nagasaki and Belfast.

But this, too, is only one aspect of the global story, one chapter of an ongoing, everyday chronicle of modern geopolitical life that adds new sections with dizzying speed. The way the US, Britain and other European powers tell it, the Mali conflict, leading to last week's Algerian spillover, flared into being almost one year ago when a northern rebellion by separatist Tuareg tribesmen sparked a coup that brought down the western-backed, elected government in Bamako. The anarchy that followed created an opening for al-Qaida and a range of Islamist groups, most notably Ansar al-Din, whose supposed aim was the conquest of the entire country. As the Tuaregs fell back, Mali's army could not hold the line. Now the French, with the backing, more or less, of their American and Nato allies, have gallantly stepped into the breach, or so the story goes.

Told another way, the entire episode is yet another vivid illustration of what happens when the west, with the former colonial powers to the fore, forgets all that has gone before and plunges into complex situations of which its ignorance far outweighs its capacity to act for the greater good. It is a fact that the Tuaregs have sought for many decades a degree of autonomy in the uncharted lands of the Sahel they call their own. The latest Tuareg rebellion arose directly from the chaos in Libya engendered by the Anglo-French intervention against Colonel Muammar Gaddafi. It is a fact that Gaddafi's arsenals provided the weapons and ammunition that eventually fatally destabilised the Bamako government. It is also a fact that this amounted to a considerable western own goal, since the Mali coup leader, Captain Amadou Sanogo, was educated, trained and equipped, at considerable expense, by the US military, as were other commanders who defected to the rebels. It is a fact that the US and the EU sought in recent years to make Mali a sort of bulwark against extremism, a model democracy in the desert, but in merely scratching the surface of a nation that was already in crisis, succeeded only in turning it into a staging post in the wider global conflict.

Looked at from yet further back, and for all its remoteness from western consciousness, Mali fits well into the larger, moving picture of which recent events provide but a snapshot. Not unlike Darfur and parts of northern Sudan, Ethiopia's Ogaden region and Somalia, Mali's chronic political instability boils down in large part to a competition for diminishing resources, for productive land and water supplies that grow scarce as desertification proceeds apace. This crisis is one of persistent drought and endemic malnutrition, as aid agencies such as Save the Children and Oxfam can testify. It is a crisis brought about in part by climate change. And it kills more children every day than any Islamist insurgency ever will. But this is not a cause deemed worthy of international intervention.

Mali, little known or not, now belongs inside the arc of instability that was once defined as stretching from Afghanistan, in the days when the Taliban took charge, through Pakistan to the Middle East and the Horn of Africa via Iraq and Yemen. Now the arc is rapidly extending westwards beyond the Arab lands to Nigeria, west Africa and the Atlantic seaboard. The common denominators are poverty, underdevelopment, illiteracy, mass youth unemployment, misgovernance, authoritarianism, corruption, suppression of women's rights and of human and civil rights in general. All this and western political and commercial meddling, too.

Little wonder extreme distortions of Islam take root amid such hopelessness and betrayal. From the Boko Haram jihadis of north-east Nigeria to Mokhtar's Algerian Salafis to the al-Shabaab fanatics of Somalia, the false prophets of violence gain sway in the absence of faith – faith that there is a better way, faith that westerners care about more than merely our own safety and comfort. From out of this arc of suffering a great cry goes up, but we barely hear it. We put our hands to our ears.

Despite all this disassociation, despite the looking the other way and the simplistic analysis pitting cut-throat, dynamite-wielding Islamist killers against innocents abroad, this bigger story in which Mali's plight is now entangled ultimately involves us all, more intimately and continuously than could any random threat of a terror bomb in Paris or London. A major shift in perception and in action is required. Otherwise, be it indirectly through mass migration, people trafficking, arms and drugs smuggling, epidemic disease, the pernicious poison of official corruption and abuse; or directly through resulting, premeditated ethnic and sectarian, religion-based violence, the nonchalant, unthinking condemnation of a vast swath of humanity to impoverishment, physical, material and spiritual, will inevitably return to haunt the more fortunate peoples of the west.